This research will be performed primarily at the Shanghai Institute of Biochemistry in China as an extension of NIH grant #R37 HD04466, the parent grant for this project. The Principal and Co-Investigators of this parent grant are Frank S. French, M.D. and Susan H. Hall, PhD., the Laboratories for Reproductive Biology of the University of North Carolina at Chapel Hill. The long-term objective is to identify human epididymal targets for male contraception by investigating epididymis-specific proteins involved in sperm maturation and fertilization. The study is part of a larger contraceptive development project involving a collaboration of the Laboratories for Reproductive Biology with Professor AJ Rao at the Indian Institute of Sciences for evaluation of lead proteins in monkeys and Dr. Catherine VandeVoort at University of California, Davis Primate Center, to test the effects of immunization against epididymis secretory proteins on sperm function in monkeys. Specific Aim 1 Define expression of the human proteins corresponding to monkey Clones ESC46I-ribonuclease A and ESC615-carboxylesterase B, Specific Aim 2 Determine the functions of the human ESC461 protein Specific Aim 3 Determine the functions of ESC615 protein Specific Aim 4 Evaluate additional epididymis-specific clones for potential as male contraceptives From a macaque epididymis-specific cDNA library containing novel cDNAs related to known gene families, two are selected for in depth study. One, ESC461 is related to the eosinophil ribonucleases A2 and A3 which have antimicrobial activity. The other, SC615 is related to the carboxylesterases which may have roles in modification of sperm surface proteins. To investigate where the proteins are expressed and localized in the human epididymis and whether they bind sperm, human clones will be obtained and recombinant protein produced and used to raise antibodies in rabbits. Recombinant proteins produced in bacteria or in eukaryotes will be used to determine the ability of ESC46I to bind and hydrolyze RNA and to inhibit the growth of bacteria. The ability of SC615-carboxylesterase to catalyze the hydrolysis of a range of substrates will be determined. If time permits, studies will be initiated on 2 other clones from this library encoding lipocalin-like proteins.